HYSPLIT Forum: hysplitbbs.arl.noaa.gov

Hello,

I am running backward trajectories on Hysplit with a high altitude starting point (Chacaltaya, Bolivian Andes; latitude 16° 20' 47'' S, longitude 68° 07' 44'' W, height according to Google Earth ~5350m). I plotted terrain height along trajectory with the vertical plot height units in Meters AGL, and surprisingly the resulting plot outputs a starting point at 3200m ASL. This questioned me: how does Hysplit determine the ground level on which are based the model's altitude outputs? I am hoping that could help me understand the ~2000 m altitude difference at the trajectory starting point.

Thank you for any answer!

HYSPLIT can use heights above ground level (AGL) or above sea level (ASL). The default is AGL. When using ASL, HYSPLIT determines the terraing height from the input meteorological data.